Exhaust- Dual 3's, single 3.5, or single 4 inch?
#1
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Exhaust- Dual 3's, single 3.5, or single 4 inch?
Car is currently making 740whp with dual 3 inch down pipes only (Twin turbo). I am in the middle of making a full exhaust and would not mind hearing people's opinions. I want it to be able to support a max of 1200 WHP for the future. I am leaning towards merging them to a 3.5, but feel i may be better served by a single 4. The Math says dual 3's flow the best....
What to do?
What to do?
#5
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I have 3.5 laying around-so that's why I ask about 3.5 and if their is anyone's experience, or math that supports that being an issue at 1000+
Last edited by coltboostin; 03-09-2015 at 12:08 PM.
#6
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(1) 4" pipe has a circle area of about 12.5" (2) 3" pipes combined have about 14.12" (1) 5" pipe has about 19.6" and (2) 3.5" pipes are about 19.2
I've seen a lot of dual 3" cars make a lot more than 1200HP. Does this mean it is the most efficient? No. However if your going to merge duals into a single make sure you increase or at least match inside surface area. My .02 anyways
I've seen a lot of dual 3" cars make a lot more than 1200HP. Does this mean it is the most efficient? No. However if your going to merge duals into a single make sure you increase or at least match inside surface area. My .02 anyways
#7
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(1) 4" pipe has a circle area of about 12.5" (2) 3" pipes combined have about 14.12" (1) 5" pipe has about 19.6" and (2) 3.5" pipes are about 19.2
I've seen a lot of dual 3" cars make a lot more than 1200HP. Does this mean it is the most efficient? No. However if your going to merge duals into a single make sure you increase or at least match inside surface area. My .02 anyways
I've seen a lot of dual 3" cars make a lot more than 1200HP. Does this mean it is the most efficient? No. However if your going to merge duals into a single make sure you increase or at least match inside surface area. My .02 anyways
Looks like I am now leaning towards dual 3's or a 3' cut out @ an X pipe and a since 3 or 3.5 out the back. Have a few 4inch scraps and in "eyeballing" it it would be more trouble than its worth
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I ran dual 3 vs single 4 and had more backpressure with single 4". Single 4" is smaller than dual 3. My wastegate only boostpressure dropped 2 psi when going from 4" to dual 3"
If you were to do anything go dual 3.5". Sure 3" may support it but doesnt mean its right. Theres gonna be some pressure in those pipes
If you were to do anything go dual 3.5". Sure 3" may support it but doesnt mean its right. Theres gonna be some pressure in those pipes
#10
I have dual 3" out the rear bumper. I'm making 1025 rwhp with it on. With the exhaust off it picks up about 80 rwhp just running the down pipes open. Same boost. (Yes twins also)
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I moved from dual 3" to bumper making 1009 whp to 3" downs to 3.5" a short run then into single 5", but havent had the chance to redyno with it on.
I went under axle and have to remove it to strap car down. Butt dyno is useless at these power levels. 800-1000 all feels same. But area wise the single 5" is huge compared to dual 3
I went under axle and have to remove it to strap car down. Butt dyno is useless at these power levels. 800-1000 all feels same. But area wise the single 5" is huge compared to dual 3
#15
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I moved from dual 3" to bumper making 1009 whp to 3" downs to 3.5" a short run then into single 5", but havent had the chance to redyno with it on.
I went under axle and have to remove it to strap car down. Butt dyno is useless at these power levels. 800-1000 all feels same. But area wise the single 5" is huge compared to dual 3
I went under axle and have to remove it to strap car down. Butt dyno is useless at these power levels. 800-1000 all feels same. But area wise the single 5" is huge compared to dual 3
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According to Poiselle's Law (flow through a pipe)
2.5" pipe flows 0.0220 m3/sec
3.0" " " 0.0457 "
3.5" " " 0.0846 "
4.0" pipe flows 0.1444 m3/sec
so a single 4" pipe should flow more than twin 3" pipes.
2.5" pipe flows 0.0220 m3/sec
3.0" " " 0.0457 "
3.5" " " 0.0846 "
4.0" pipe flows 0.1444 m3/sec
so a single 4" pipe should flow more than twin 3" pipes.